The present invention relates to an automatically self-steering plow/harrow combination and in particular to a harrow device arranged to be used in combination with a conventional plow, thus forming the aforementioned plow/harrow combination.
Combinations of plows and harrows are previously known, e.g. by Swedish Pat. No. 316,042 and U.S. Pats. Nos. 3,574,320; 2,568,572 and 2,951,546. The aforementioned patents dislose a harrow device attached to, or adjacent to, a plow blade. A combination of a plow and a harrow has obvious advantages, since the soil can be subjected to a light harrowing operation in connection with the plowing operation. As a result, the plow ridges are levelled, thus resulting in a faster and more even evaporation of moisture from the soil and better conditions for seeding, which creates a more even crop. By carrying out plowing and light harrowing in one operation, the creation of wheel tracks from the tractor is also avoided, a fact of great importance, since water can remain for a considerable time in the wheel tracks, thus preventing the desired even evaporation of moisture from the soil. Previously known combinations of plows and harrows consist of a harrow device attached to, or adjacent to, a plow blade. The harrow device is a conventionally shaped harrow, comprising a number of harrow teeth, directed towards the ground plane and spaced from each other, preferably having a circular cross/section. In the previously known types, of harrow devices, the harrow teeth are arranged pivoting, or springacting, in a plane corresponding to the direction of travel for the plow.